China's First Infrared Occultation Spectrometer (GaoFen-5/AIUS) Monitoring Atmosphere Above Antarctic: Evaluation of Methane Profiles

Abstract

The atmospheric infrared ultraspectral sounder (AIUS) is China's first infrared occultation spectrometer onboard the GaoFen-5 satellite. This instrument provides measurements in the near-infrared and mid-infrared spectral regions with a spectral resolution of 0.02 cm$^{-1}$, monitoring key greenhouse gases like methane (CH$_{4}$). In this study, we have developed a physics-based retrieval algorithm for accurately deriving CH$_{4}$ mole fraction profiles from infrared absorption spectra. The retrieval algorithm is applied to the AIUS and successfully obtains CH$_{4}$ mole fraction profiles from January to December 2019 over Antarctic. The validation results show that the retrieval algorithm has a satisfactory performance using AIUS measurements, with average relative standard deviation of the differences less than 7.2% throughout the altitude range of 10–70 km.

Keywords

• Antarctic
• GaoFen-5 (GF-5)/atmospheric infrared ultraspectral sounder (AIUS)
• $_{4}$ )%22%2C%22default_operator%22%3A%22AND%22%7D%7D%7D"> methane (CH<named-content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="LaTeX">$_{4}$</tex-math> </inline-formula> </named-content>)
• retrieval algorithm